I have a 1987 Cat-22. Catalina Direct tells me usual location for breakage is under swage where cable attaches to keel. Recommends replace cable every 2 years at least especially if in salt water because cannot see under the swage to rule out cable corrosion. They believe that most commmon cause of breakage is keeping the cable too loose and flapping around when boat in motion sailing. They recommend two turns on cable winch after letting keel all the way down. But this produces cable hum. Others recommend releasing winch turn or two to eliminate hum if it is annoying. Many sailors seem to love the hum and think of it as a speedometer which increases volume as boat increases speed. I believe Catalina Direct advice not correct. I believe cause of cable wear at that site must be the high vibration frequency required to produce the hum . Thus cable is preserved by always eliminating hum. My boat has been in brackish [i.e. slightly salty] water for 5 years. Because the water gets very shallow at the slip I always retract the keel fully when boat is at the slip. I have just replaced the cable for the first time and I am sure previous owner had not replace it for at least 2 more years. So, after more than 5 years in somewhat salty water I find cable in pristine condition except for break of a single strand high up on the cable. This brak may have occured because it was dragging over a severely warn , no longer rotating turning ball. I sawed open the swage. The cable looks shiny and new inder the swage. It seems to me that my theory is supported and that cable hum should be eliminated to prevent the stress of high vibration frequency where the swage clamps the cable. Moreover salt water [at least slightly salty] seems not to be a problem, at least when the leel is kept fully retracted when in port. Any comments?